Important application properties of pigments for publication printing inks are good rheology, stability, gloss, color strength and holdout i.e. the absence of color penetration through the paper stock. Azo pigments have been treated with various amines to achieve these goals. Typical references illustrating such treatments are as follows: U.S. Pat. Nos. 3,532,520 (alkyldiamines), 3,759,733 (alkyl amines or amine oxides), 4,220,473 (dimer acid based amines), 4,462,833 (linear alkyl polyamines), and DE No. 3109 579 (amines with a pyrazolone mixed coupling).
British Pat. No. 1,139,294 teaches that the incorporation of certain azoacylacetamides containing one or two nitrogen atoms into diarylide pigments can yield a product that gives improved strength and flow to printing inks. Typical amide components disclosed in this reference are acetoacet-N-(3-dimethylaminopropyl)amide, acetoacet-N-(3-octadecylaminopropyl)amide and oleylamide. It does not, however, achieve the improved results of this invention.